Power brake booster



March 11, 1958 R. QRIKE I POWER BRAKE BOOSTER Filed oct. 18. 1954 3 Sheets-SheerI 1 i INVENTOR. //CHAED 61E/KE ATTORNQY R. C. RIKE POWER BRAKE BOOSTER l March 11, 195s 3 Sheets-Sheet 2 Filed Oct. 18. 1954 IIII n i INVENTOR.

E/c HARD C.' /P/KE ATTORNY l March 11', 1958 R. c.` RIKE POWER BRAKE BOOSTER 3 Sheets-Sheet 5 Filed Oct. 18, 1954 JNVENTOR. )Pfc/AED C'. /P/KE u. Wt,

A Troia/vs Y United States Patent POWER BRAKE BOOSTER Richard C. Rike, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware v Application October 18, 1954, Serial No. 462,648

' 12 claims. (ci. t0-54.6)

This invention relates to a brake booster mechanism to provide for power actuation of the brakes of the motor vehicle.

An object of the invention is to provide a brake booster of simplified construction in which mechanical devices provide for a brake reaction feeling through the brake booster.

`Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the invention is clearly shown.

In the drawings:

Figure l is a longitudinal cross sectional view through a brake booster mechanism incorporating features of this invention.

Figure 2 is a transverse cross sectional view taken along line 2-2 of Figure 1.

Figure 3 is a longitudinal cross sectional view of a portion of the mechanism taken along line 3--3 of Fig. 2.

Figure 4 is a longitudinal cross sectional view like that of Fig. 3 but illustrating the valve mechanism in an operating position.

Figure 5 is a transverse cross sectional view taken along line 5 5 of Figure l.

Figure 6 is a perspective elevational view of the piston unit for the device.

Figure 7 is a perspective elevational view of one of the reaction plates of the reaction mechanism.

ln this invention the brake booster mechanism comprises a fluid motor 10 that consists of a housing or casing 11 in which a piston unit 12 operates in a reciprocal manner. The huid motor 10 is adapted to be operated by differential of pressure applied on opposite sides of the piston unit i2, the differential of pressure being obtained by evacuating the housing 11 on one side of the piston unit 12 whereby the piston unit will be caused to move in one direction. A compression spring 13 normally retains the piston unit 12 in the position shown in Figure 1.

The piston unit 12 carries a displacement member or plunger 14 that enters a hydraulic fluid master cylinder 15 through a multiple seal structure 17.

The master cylinder 15 is mounted on the closed end 18 of the housing 11. The opposite end of the housing 11 is closed by means of a cover member 19 secured thereto bythe bolts 20.

When the` plunger 14 enters the master cylinder 15 to displace hydraulic iluid therefrom, the hydraulic ilud passes through the discharge port 21 into the check valve chamber 22 and thence through the check valve 23 into the fitting 24 having the discharge port 25. The check valve 23 also provides for retaining a predetermined low value hydraulic fluid pressure in the hydraulic lines of the hydraulic brake system in conventional manner, the brake lines of the hydraulic system receiving fluid from the discharge port 25.

The master cylinder ,l5'is integral with a reservoir 26 that has" the reservoir cavity 27 provided with a closure 2,826,041 Patented Mar. 11, 1958 "ice cap 28 that has a removable ller cap 29 provided there- The piston unit 12 comprises a generally annular body 30 that has a resilient seal structure 31 between the body 30 and the inner wall 32 of the housing 11. The seal structure 31 is retained on the body 30 by a wall or cap member 33 held thereon by bolts 34.

The annular body has a recess forming a coaxial annular chamber 35 that receives a valve mechanism 4@ to control uid flow to the right hand side of the piston unit 12, as viewed in Fig. 1. Coaxial with the chamber 35 there is provided a boss 36 that has the coaxial bore 37 that receives a cylindrical valve element 38. rl`he valve element 38 is retained within the bore 37 by means of a washer 39 and a snap ring 4l. The cylindrical valve element 38 is provided with an internal bore 42 that receives the end of a manually operable member 43 that is embedded in the rubber-like member 44 within the bore 42. The member 44 is retained in the bore 42 by means of a washer 45 and a snap ring 46. The manually operable member 43 is connected with the brake pedal of a motor vehicle in any conventional manner for longitudinal reciprocal movement of the member 43 upon actuation of the brake pedal. A rubber-like boot 47 extends between the member 43 and the end Wall 19 of the casing to prevent entry of dirt through the wall 19.

The cylindrical valve member 38 has a coaxial annular valve face 50 that normally is in spaced relation with a resilient rubber-like valve seat 51 carried in a movable member 52 that is supported in the chamber 3S by means of a llexible diaphragm wall 53.

The valve seat 51 normally engages a valve face 54 that is coaxial with the valve face 50 and spaced radially therefrom, the valve face 54 extending slightly in advance of the valve face 50 when the valve mechanism is in the released position, or off position, as illustrated in Figure l.

The chamber 35 in the piston unit body 30 is provided with a radial passage 58 that has a side opening 55 connected with a ilexible rubber-like tube 56 that extends through the wall 11 of the fluid motor 10 and is adapted to be connected to a source of vacuum power ou a motor vehicle with which the device is associated.

The end of the passage 58 is closed by a ball 57 being driven into the end of the opening.

The cylindrical valve element 38 has a reduced diameter portion 70 that extends through the axial bore 71 provided in the member 52, the reduced diameter portion 70 terminating in a further reduced diameter portion 72 that provides a shoulder 73.

A light compression spring is received within an axial bore 76 in the valve member 38 with one end engaging the bottom of the bore 76 and the opposite end engaging the left hand of the displacement member or plunger 14 that extends through the wall or cap member 33 and is journaled therein. The spring 75 maintains the valve element 38 normally in predetermined spaced relationship with the end of the plunger or displacement member 14, shown in Fig. l.

The body member 30 of the piston unit 12 has a recess therein forming a chamber 80 that is closed by the cap member 33, a seal member 81 being provided between the attached parts. The compression spring 13 normally retains the piston member unit 12 in the position shown in Fig. l with the resilient bumper 82 engaging the wall 19 of the motor housing.

To provide for admission of atmospheric pressure into the housing 11 to establish pressure differential on opposite sides of the piston unit 12 when the right hand side of the piston unit is connected with a source of vacuum, the housing 11 is provided with openings 85 that are covered with an air lter 86 retained in place by a protective cover87, as shown in Figure 2f A suitable resilient gasket is provided between the air lter 86 and "theihousing 11 to` prevent air' bylpassing thelter unit.

Atmospheric air enters the chamber 90 on the left hand sideof the piston unit lz-.andpasses through..-openings 91 provided in'the wall of the body member 30, as shown in Fig. 3,.that the air can enter the chamber.80. From the chamber SV the atmospheric. air :pressure canpass through the bore 71 inthemember 52 and between the valve ,face 50 andtheresilient seat-Slinto the chamber 95.

The-chamber 95 is connectedby means of the radial passage. 96 and the angular passage 97 in the piston body 30, and through the opening 98 in the cap'member 33 with theright hand side ofthe piston unit 12, shown in Figure 1. The radially outer end ofthe passage-96 is closed by means ofthe friction pressed ball 99 therein. It will `therefore be apparent that when the piston unit 12 is inthe position shown inl Figures 1 and 3 andthe valve mechanism is in the position shown, atmospheric pressure is present on both sides ofthe piston unit 12. This type of brake booster mechanism is commonly known as an air suspended unit.

When using power actuated brake booster mechanism it is necessary that some means be provided to sense the brake action for transmission to the brake pedal and thus be felt vby the operator ofthe vehicle, or else over-braking vwill occur-and ythere wouldbe nofeel ofbraking elort. fIt'is therefore desirable to have a mechanism incorporated inabrake booster'that is actuated by the brake reaction of the' hydraulic fluidv inr the-master cylinder'to'elfect a reaction'to the brake pedal'that vgives a `feel to the operatorof a braking operation, and 'yet this Vreaction force must not be so great as to be equivalent to a brake action required by direct pedal action as though `no brake booster mechanismfwere in operation. .'-Thei-purpose of the brake booster is to reduce thepedallfortrequired in a braking operatiom and yet the feel'of the braking operation must not `be such as to affectfa' rapid 'fall of the pedal as'though no brake action-occurred andthe reaction mustnot be so great as to 'beequivalent toria straight mechanical action.

LIthas been common in brake boosters of the prior art to :provide a`r plunger or sleeve either in or around `the displacement Vplunger that operates in the mastercylinder so that pressure of thefhydraulic uid in the master cylinderfwould react on the supplementary sleeve Vor plunger to effect a brakelrea'ction thatewouldgbe transmitted 'through fthe-3 brake' vbooster to the "pedal 1 operated memberY thereof -to obtain a brakefeel in; thebrake pedal. lnf'this yinvention' there "-is'V provided a reaction' device thatincldes -a rst 'reaction element or` discy 100 that is carried on the end of the displacement'member 14 and islfpositioned in-'the chamber 80 ofthe p'i'stonunitflZ.

yi'e'atz'tionelement 100 is retained on `the "displace menti-member -14 bymeans of aisnap ring 101. Thereaetion'el'ement 100is` preferablyinthe form .bof an 'annularringand'has a raised ring portion 102 near'the outer e'dge periphery v-to-provide a pivot'line.

"Ase'cond reaction element or disc 105`is carried uponI the-reduced; diameter portion 72 of the valve element 38 and is disposed within the chamber 80 of the pistonbody 30.r Thereaction element105Y is preferably annular 1in shapelandehas van annular raised ring portion 106 Lthat providesV an'annular pivotline. y

A.pluralityJof-reaction plates` orJinge'rs 110`.are` placed between-the reaction elements 1004 and 105, ,the reaction elements '100"'and 105 engaging opposite` sides ofv the -re actionA plates 110.

as-shovvn vin the perpectiveview of Figure-f6. :Each of.'

these recesses 115 has transversely extending notches 116 and 117 on opposite sides thereof to receive the ears 111 of the reaction plates 110, as shown in Figure 5. The stem portion of the reaction plates 110 extend through the opening 118 of the recess 115. The notches 116 and 117 therefore provide shouldered portions in which the ears 111 of the reaction pilates" 110 are pivoted. Substantially in linewith the notches 116'and 117 there is provided the raised portion 120 on which the head portion ofthe reaction plates 110 ispivotally engaged.

As shown in Figure 5`the reaction plates t110D-are radially disposed relative to the axis of the piston unit 12, and astshown in Figurell 'thereactionplates 110 are disposed substantially in a common plane between the reaction elements y100`"arid 15"'w'th`the reaction elements engaging opposite sides of the reaction plates.

A compression spring 125' is placed between the reactionplates 110 Yand a retainer 126 that holds the outer periphery of the diaphragmSS insealingengagement with the shoulder 127 of the chamber 35. Also,nthe compression spring 125 engaging the reaction platesv-110 urges them to pivot more about theraised portions 120 engaged by the head portion of the reactionplate to -hold one face of the reaction plates against the annularfpivot ring v`1020i? the'reaction plate 100. A'second compression'spring 130.is provided'be'tween the second reaction element 5105 and the inner periphery of 'thediaphragm support member53. 'This spring 130 urges the member 52 in a left hand direction to maintainthe vresilient-seat 51fagainst'the-valve` face 54 and also urgesA the reaction element e105 in a right handdirection to maintain the pivot ring 106 of the reaction element 105 in engagement withthe inner ends of the reaction element 105 in spaced relationship to the shoulder 73 on the valve element 38. The spring 75 also aids in maintaining the spacedrelationship'between the reaction element 105 andthe shoulder 73 on thevalve 'element 38.

Operation When -the brakes .are in released condition, thevarious components of the brake boosterassume `the positions illustrated in Figures 1 and 3. At` this time atmospheric air is present on both sides of the piston unit 12, the-air being i admitted directly into chamber 90 through :the openings 85 from the air iilter 86 and to the chamber 90agon. theoppositefside of'lthe piston through the openipgs.;91, chamber 80, bore 71,- valve 'opening betweenfthe j. and, 3. .Therst movement ofthismember 43 causes the valveface 50.to.engagethe resilient seat 51 with resultant compressionxo'f the light spring 75 thus closing off chamber 95 from the bore 71 and preventing further admission ofatmospherieair kthrough the ypassages 96, 97 and98i11to thechamber 90a ofthe-housing 11. `Up to thistime no power assistance has Vbeenobtainedfrom the booster, nor has eany :brake` applicationibeenmade 'because'the displacementfmember- 1'4hasr-.noty'et beenmoved into'the masterloylinder v-15.\ "Merely thellight spring 75 has been compressed, this requiring practically no'pedal eiort to accomplish'. -fSli'ght'furtherfmovement of' the pedal operated memb'erl43-in arght'hand 'direction willv clause the valve`fseati-`51 'tobe removedff-from` the "valve face'"54 therebywpening#chamber-35 to'chamber 95, as 'shown inFigurefli whereby .thei source ofvacuum is connected with chanibr 95fand ythrough passages .961 and 97 and opening'f98'withthe'rchamb'er 90d of the housing 11 to evacuatechamber-90a. At this'time there-fore, atmosple'iic aripress'ur'ef's't'ands in'chamber`90 and'le'siser than atmospheric pressure stands inrchamber 9021 to obtain a pressure 'differential-onfopposite sides of "the piston Vvunit 12 `toieatise`=`-tl`1e pistonA unit-*12v t'o move in'a ighth'and asseoir direction. Upto this time the only resistance Amadeby the pedal of the vehicle is the light resistance of the spring 75.l i

' When the pressure dilerential is lestablished `on the piston unit 12 `and it begins to move in al right hand di-v rection the piston unit will carry therdisplacement member 14 ina right hand direction through the reaction plates 110 and the reaction element 100. Concurrently, that is when the displacement member 14 moves into the master cylinder 15 as a result of the action of the power actuated piston unit 12, the hydraulic pressure created in the master cylinder 15 will react on the end of the displacement member 14 within Vthe master cylinder 15 urging it in a left hand direction. This brake reaction of the hydraulic pressure uid will cause the reaction plates 110 to pivot about their pivot ledges 120 and move the reaction element S into engagement with the shoulder 73 on the valve member 38 whereby the hydraulic reaction force of the hydraulic fluid in the brake cylinder is transmitted through the displacement member 14 to the piston unit 12 and the valve element 38, and from the valve element 38 to the manually operable member 43 to establish brake feel at the brake pedal of the vehicle.

The only time that the end of the reduced diameter portion 72 of the valve element 38 directly engages the left hand end of the displacement member 14 is when there is a failure of the vacuum source for power actuation of the piston unit. In this manner direct brake action can be obtained through the direct connection from the valve element 38 to the displacement member 14.

The valve mechanism heretofore described is of the follow-up type in that when the brake action is sufficiently strong and the operator tends to stop further movement of the brake pedal, the resilient valve seat 51 will be engaging both valve faces 50 and 54 to hold the plunger 14 inthe attained position without any change in` pressure conditions on either side of the piston unit 12.` The positions of the valve shown in Figure 1 and in Figure 4 provide for either balancing of the atmospheric pressure on both sides of the piston unit 12 or evacuation of chamber 90a of the booster unit to cause advancement of the piston unit 12.

The engagement of the reaction element 100 with the reaction plates 110 is radially outside engagement of the reaction element 105 with the reaction plates 110 with the pivot connection of the reaction plates 110 being radially outside the engagement of the reaction element 100 with the reaction plates 110 whereby the hydraulic reaction forces from the displacement member eiected by the hydraulic pressure tluid in the master cylinder 15 are proportioned to the actuating force of the piston unit 12 to obtain a desired percentage of reaction feel to the manually operated member 43. The percentage of re action forces that are felt through the manually operated member 43 can be changed by changing the pivot connections with the reaction plate 110, that is varying the radial position of the pivot rings 102 and 106 relative to each other.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other froms might be adopted as may come within the scope of the claims which follow.

What is claimed is as follows:

1. A brake booster mechanism comprising, a uid pressure operated motor including a casing having a pressure differential responsive piston unit operable therein, a master cylinder, a hydraulic fluid displacement member operable in said master cylinder and connected to said piston unit for actuation thereby, a follow-up control valve mechanism carried by said piston unit, and having one position to establish equivalent pressures on opposite sides of said piston unit to inactivate the piston and a second position in which to establish differential pressures on opposite sides of said piston unit to activate the piston, said control valve mechanism including a manually operable member to actuate the valve mechanism, resilient spring means between said manually operable member and said displacement member normally to position said valve mechanism in said one position, a first reaction element on said displacement member, a second reaction` element on said manually operable member and movable relative to the same and relative to said first reaction element, stop means on said manually operable member engageable by said second reaction element, spring means resiliently maintaining said second reaction element normally out of engagement with said stop means, and a plurality of fingers between said reaction elements and carried Von said piston unit in free suspension with said reaction elements engaging said fingers on opposite sides thereof and radially inwardly of the suspension of said fingers on said piston unit.

`2. A brake booster mechanism in accordance with claim l in which the said ngers are substantially T- shaped with the head portion thereof providing the support for the fingers and the end of the stem portion engaging the said second reaction element.

3. A brake booster mechanism in accordance with claim 1 in which the first reaction element engages the lever means radially outside engagement of the lever means by said second reaction element and the lever means engages the piston unit radially outside engagement thereof by said first reaction element to proportion the reaction forces transmitted to the valve mechanism tothe actuation force of the piston.

4.,A brake booster mechanism in accordance with,

claim l in which the rst reaction element engages the lever means radially outside engagement of the ,lever means by said second reaction element and the lever means engages the piston unit radially outside engagement thereof by said first reaction element with the second reaction element and said piston unit engaging said lever means on one side thereof and the rst reaction element engaging the lever means on the opposite side to proportion the reaction forces transmitted to the valve mechanism to the actuation force of the pistou.

5. A brake booster mechanism in accordance with claim l in which the pivotal connection of the lever means with the piston unit is radially outside the engagement of the first reaction element with the lever means and the engagement of the first reaction element with the lever means is radially outside the engagement of the second reaction element with the lever means, said reaction elements engaging the said lever means on opposite sides thereof.

6. A brake booster mechanism comprising, a fluid pressure operated motor including a casing having a pressure differential responsive piston unit operable therein, a master cylinder, a hydraulic uid displacement member operable in said master cylinder and connected to said piston unit for actuation thereby, a follow-up control valve mechanism carried by said piston unit, and

having one position in which to establish equivalent pres.

sures on opposite sides of said piston unit to inactivate the piston and a second position in which to establish differential pressures on opposite sides of said piston unit to activate the piston, said control valve mechanism including a manually operable member to actuate the valve mechanism, a first annular reaction ring on the displacement member, a second annular reaction ring on the manually operable member, and a plurality of at reaction plates betwen the said reaction rings pivotally supported on the piston unit with the rings disposed on opposite sides of the plates, and engaging the same at radially spaced points whereby the first reaction ring aetuates the reaction plates to effect reaction on the second reaction ring to transmit hydraulic reaction forces from the displacement member to the valve mechanism proportioned to the actuating force of the piston unit.

7. A brake booster mechanism in accordance with claim 6 in which the reaction platesl are disposed in a ageaaoei 4r151mm rrairgemenrradiany disposed abonarse -axis? ofethep'istonfunit. "58.I A brakeboosterfmechanismpin accordance vvith `cl`im-`6 in` Lwhichtthe' reaction Vplates are disposed in a fcommoniplanar arrangement 'radially i disposed about the axisrof"the"piston"unit with 'each of the plates being substantially "Tsha'pedlg said v"piston unit having paired shouldershereon engaged by `the head portion of the Tf'shaped' plates pivotally supporting the respectiveplates onr'therpistonl 'unitffth'eV end'of the fstem portion of the said platesengaging "the, second reaction ring, the rst reactionring beingfdisposed between the engagement of 'the4 second jreaction ringy with 'the plates and thefpivotal mountipg ofthej plates on'fthe piston unit. 9.a"l'"brake"booster mechanism Vcomprising, ,a fluid pressure` operatedimotor includingk a ,casingrhaving a pressure jdifferential responsive piston unit operable therein, 'a'ma'ster cylinder, ahydraulicluidl displacement *member operable in said master'cylindenand connected to'saidipiston' unif'fo'r actuation thereby, a\ followup control.. valve'me'chanism carried by said-piston unit, and'having oneY positionin which to establish equivalent pressures on'oppsite sides of saidpiston unit.to inactivate the "piston and 'a second position :inv whichto establis-h"differential4 pressures on .opposite sideslof .said pi'stonu'nit to activate thepistong. said .controlivalve mechanisminclding a lmanually Y operable member to attuate' the valve 'm`e'cliani'sm said. pi'stonfunitlhairing` one face thereof provided witha cox/erl plate cooperating with thejjpistonlimit to'lform. anfar'mularizcavity coaxial withthelaxis f fthe `piston nnit,f.a lirstfannulanreaction ring on thedisplac'emient member ints'aidcavityfra' second annular reaction. ring on thev-`manuallyl operable"member in.rsaidr.cavity,@plurality of reaction plates' betweemthe reaction ringsffandaengaged `on opposite sidesrfthereby, saidaplates pivotally ieng'aging lfthezrpiston unit, :whereby to 1effect ytransmissie!ny off-hydraulic? reactiorr forces `from 8 the "@'displajcement 'member to said manually i operable member.

`10. Ak brake booster mechanism in accordancelwith claim 9 in which the pistonunit has openings thereinsfor passage of uid from one side of the piston unit into the, saidcavity,and the 'said Valve .means controls `ow of fluid lfrom the said cavity to the opposite side of the piston unit.

1l. A brake booster mechanism in accordance with claim 9 -that includes resilient spring meansbetween said secondneaction ring and the valve mechanismfto position vthe said second reaction ring in spaced relationship to Ystoprmeans on the manually operable `member Wherebysaidrvalve mechanism can be operatedbyrthe manually," operable member,` prior to reaction engagement thereof by. saidsecond reaction ring.

` 12. VA`.brake booster mechanism in accordance .with claim `9that1includes resilient spring means between said valve mechanism .aud the displacement member normally to maintain 'saidvalve mechanism in predetermined spaced relationship relative to v.said displacement -member, rand which also includes .resilient spring means'betweensaid secondn reaction ring and. said valve mechanismnormally to maintain predetermined spaced relationship rbetween said secondsreactionring andstoprmeaus `onfsaid manually `operahlemember.whereby toA provideV forv` actuation ofr said `.valve mechanism relativeloV said. displacement memberiand :said second.. reaction .ring z prior to. freaction engagementlo said\,second-.reaction ringfwith `the stop means orn thefvalvemechanism.

References Cited inthele of this ,patent UNITED; STATES'. PATENTS 1.-,620g5l'3 'Braggwet al. ";.-Mar.8, l:1'527 275,697 xsfelzer Man-10; i942 2457,721 'Price :Dec. 283-11948 2,646,665 l'Rockwell *July '-28,":1`953 

